Phase 3 study

Reproduced exactly, unedited. Written for researchers rather than for patients.

Inclusion criteria:

1. Must have completed the dosing planned in the primary pediatric guselkumab study. 2. Received benefit from continued guselkumab therapy in the opinion of the investigator. 3. Before enrollment, a participant must be (as defined in Section 10.4) either: a. Not of childbearing potential, OR b. Of childbearing potential and not sexually active, practicing abstinence or a highly effective method of contraception (failure rate of <1% per year when used consistently and correctly) and agrees to remain on a highly effective method while receiving study intervention and until 12 weeks after the last dose - the end of relevant systemic exposure. The investigator should evaluate the potential for contraceptive method failure (eg, noncompliance, recently initiated). Examples of highly effective methods of contraception are located in Section 10.4. 4. Participants of childbearing potential must agree not to donate eggs (ova, oocytes) or freeze for future use for the purposes of assisted reproduction during the study and for a minimum of 12 weeks after receiving the last dose of study intervention. 5. During the study and for a minimum of 12 weeks after receiving the last dose of study intervention, a participant capable of producing sperm or ejaculate: a. who is sexually active with an individual of childbearing potential must agree to use a barrier method of contraception (eg, condom with spermicidal foam/gel/film/cream/suppository) b. who is sexually active with an individual who is pregnant must use a condom c. must agree not to donate sperm. 6. Parent(s) (preferably both if available or as per local requirements) or their legally designated representative must sign an ICF indicating that they understand the purpose of, and procedures required for, the study and is/are willing to allow the child to participate in the study. Assent is also required of children capable of understanding the nature of the study (typically 7 years of age and older) as described in Informed Consent Process in Section 10.2.3. An adolescent who signs the assent form will be given the opportunity to sign an adult ICF at a later visit when they reach the age of majority during the study indicating that the participant understands the purpose of, and procedures required for, the study and is willing to participate in the study. 7. Must be willing and able to adhere to the lifestyle restrictions specified in this protocol, see Section 5.3.

Exclusion criteria:

1. Is ≥18 years of age and resides in a country where 2 years have elapsed post-marketing authorization for the respective adult indication. Is <18 years of age and resides in a county where 2 years have elapsed post-marketing authorization for the respective pediatric indication. 2. Are pregnant, nursing, or planning pregnancy or fathering a child. 3. Taken any disallowed therapies as noted in Section 6.9.1, before the planned first LTE dose of study intervention. 4. Employee of the investigator or study site, with direct involvement in the proposed study or other studies under the direction of that investigator or study site, as well as family members of the employees or the investigator. 5. Any condition for which, in the opinion of the investigator, participation would not be in the best interest of the participant (e.g., compromise the well-being) or that could prevent, limit, or confound the protocol-specified assessments.